1. Field of the Invention
The present invention generally relates to a system and method for gathering seismic data. In particular, the present invention relates to a system and method for enhancing the collection and ease of such data and determining various conditions associated with such seismic receivers.
2. Description of Prior Art
In the typical prior art, seismic exploration employs an energy source to impart energy into an object, such as the ground. The various energies strike various formations and are reflected or refracted.
Receivers are employed in a pattern to pick up the returning waves. These receivers pick up the returning wave and convert the received energy into another signal that may be transmitted to a collection station. In typical operation, the receivers convert the received energies into an analog electric signal.
In typical operation, the receivers (or “phones”) are strung together in streamers. The signals are thus transmitted in an additive fashion, and the collection device only receives the “summation” signal of a group of streamers. The collection device may then digitize this stream and either store it or retransmit the data corresponding to the signal. In this manner, when a single receiver fails, detection and amelioration of the problem is hampered, since an operator cannot discern easily which phone has been compromised, let alone which component of the phone has failed or falls outside of operating tolerances. In this case, each phone must be individually tested until the culprit is found. This adds time and expense to many seismic surveys.
Thus, antenna effect problems of each phone, ground roll, direct line energy from the source, or other combinations of signal degradation may hamper the viability of numerous readings. If one phone is not working in specification, then the data from the entire streamer may also be compromised.
Additional problems are introduced when the phones are placed on a varying plane. In this case, the seismic breaks contain an additional offset not related to their distance apart in an x-y plane. When the arriving seismic energy comes to each detector, the breaks appear as a function of the distance the seismic receptor is from the source, as well as the geometry and properties of the reflective and refractive subsurface features. In the typical streamer, an offset may be used to compensate for this time lag due to these features.
In many typical systems, however, the streamers are not aligned on perfectly flat surfaces. In this case, the offsets will vary as the height of the point where the phone is relative to that of its kindred on the streamer. As such, a different static must be used to offset the height difference of the individual phones, and a potentially different static correction must be made for every phone that “adds” its signal to the overall trace. In this manner, the collection of the seismic data from an aggregation of phones suffers from inaccuracies introduced in the process, and which cannot be easily backed out.
Additionally, new add-on modules to the phones add complexity to the set up of the seismic survey. Many typical crewmembers, or doodlebuggers, lack skilled training to add units to a streamer. Many doodlebuggers are not easily retrained on new equipment. As such, the introduction of “add-on” modules to the seismic receptors is not easily or effectively accomplished in all cases.
Additionally, such modules need to be stored when not in use, packed up for new surveys, and re-laid for each new array geometry. Thus, the additional modular units add to the time necessary to prepare, conduct, and dissemble for each survey. Further, the additional modular connections increase the chances for potential failures, as well as increase the cost of the overall instrumentation needed for the performance of the survey.
As such, many typical seismic detection systems suffer from deficiencies in providing accurate indications of defects. Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.